The present invention relates to a method of producing a laminated-type electrostrictive effect element which makes use of the longitudinal electrostrictive effect.
The copending U.S. patent application Ser. No. 493,583 discloses a laminated-type electrostrictive effect element having a plurality of thin plates made of an electrostrictive material and a plurality of alternating, superposed internal electrodes. Alternate internal electrodes are connected in common to form a first and a second group of electrodes and supplied with positive and negative voltages, respectively, by an external power supply so as to produce a longitudinal electrostrictive strain in the direction of lamination. Because of the use of the thin electrostrictive plates, this laminated-type electrostrictive effect element can operate at a low voltage. In addition, a large strain effect, i.e., a large displacement, is ensured due to the laminated structure. For these reasons, this electrostrictive effect element is expected to find various uses in a printer head of an impact printer, in a relay, and so forth.
However, it is difficult to electrically connect the electrodes of each of the groups of electrodes in common and to the external power supply. This is due to the extremely small distance between adjacent internal electrodes which is as small as several tens of microns to one millimeter, resulting from the use of very thin plates of electrostrictive material.
To obviate this problem, the above-mentioned U.S. patent application Ser. No. 493,583 proposes to form an insulating layer of a stretchable, flexible, soft organic material on the exposed side ends of the internal electrodes which are not to be connected electrically. The insulating layer made of the organic material, however, exhibits an inferior adhesion to ceramics, metals or the like material. In addition, the organic material exhibits an inferior moisture-proofness. For these reasons, the organic material cannot provide satisfactory electric insulation in the electrostrictive element which is subjected to a high voltage. Particularly, in the laminated-type electrostrictive effect element, a high voltage of several tens to several hundreds of volts is applied between adjacent internal electrodes, a distance as small as several tens of microns to 1 millimeter. Thus it is difficult to obtain a practical element with an insulating layer of organic material.